This invention relates to golf balls and in particular to golf balls having dimples formed on the surface. The golf balls are of conventional design in the sense that specifications of the United States Golf Association are complied with from the standpoint of parameters such as an outer diameter of a minimum of 1.680 inches. Similarly, conventional dimple depths of about 0.01 to about 0.015 inches are contemplated.
In the manufacture of golf balls of either a two-piece or three-piece variety, one method used is compression molding wherein two hemispherical cover shells are applied over a core and joined at the equatorial seam by heat and pressure. This results in a "seam line" free of any dimples which creates certain functional and aesthetic problems. As to function, non-uniformity of the dimple pattern yields less satisfactory results from the standpoint of consistency of performance.
From an aesthetic point of view, if the golf balls are randomly oriented for imprinting of trademarks and other information thereon, the seam line can create the optical illusion that the ball is not spherical, or can otherwise give the impression of an improperly produced ball. For this reason, it has been necessary to carefully orient some balls before imprinting in order to produce a ball with the best possible appearance.
One solution to the foregoing problem is disclosed in U.S. Pat. No. 4,932,664, issued Jun. 12, 1990 to Pocklington et al. and assigned to the common assignee, which patent is incorporated herein by reference in its entirety. In that patent, a golf ball is disclosed wherein the dimples are evenly distributed over the surface and are arranged in three different patterns comprising a pentagon formation at each of the poles, five equally-spaced trapezoid formations in each hemisphere, and five equally-spaced triangular formations in each hemisphere interposed between the trapezoid formations. This golf ball construction successfully minimizes the appearance and effect of an unbroken seam line. It would be desirable, however, to provide a golf ball construction with these same advantages, and also with even further improvements in aerodynamic properties while still complying with the aerodynamic symmetry requirements of the United States Golf Association, which state in part that the ball shall be designed to perform in general as if it were spherically symmetrical.